A cloud is nothing more than a shotgun blast of (x,y) points defining a mesh. The actual mesh is computed from the points by Delaunay triangularization. The <field> contains a <mesh> attribute with the name output.cloud(m2d), which points to our cloud as the underlying mesh. Each value in the field corresponds to a point in the cloud. The first value is for the first point in the cloud, the second for the second point, and so forth.

A cloud can also be defined with (x,y,z) points, which are triangularized into a tetrahedra to form a 3D mesh. But other than that, the example is the same. The <field> contains a <mesh> that points to the output.cloud(m3d) mesh, and then defines values for each point in the mesh.